Soft, over-molded material. Inside rails fit snugly against mouthpiece. Will not crack or chip if dropped. Designed for inverted ligatures that fit hard rubber tenor saxophone mouthpieces. . .
 
The D'Addario mouthpiece cap for Tenor is made of flexible material and features rails that fit snugly against the mouthpiece. That way, if you accidentally drop your mouthpiece cap, it will not break or chip.
Makes less noise when dropped